Classification of plants

1. Classification
of Plants
By Asst. Prof .Nilima Kamlu

2. Plant Kingdom – Plantae
Kingdom Plantae includes all the plants.
They are eukaryotic, multicellular and autotrophic organisms.
The plant cell contains a rigid cell wall.
Plants have chloroplast and chlorophyll pigment, which is required
for the photosynthesis

3. Classification is based on the
following criteria:
– Plant body: Presence or absence of a well-differentiated plant
body. E.g. Root, Stem and Leaves.
– Vascular system: Presence or absence of a vascular system for the
transportation of water and other substances. E.g. Phloem and
Xylem.
– Seed formation: Presence or absence of flowers and seeds and if
the seeds are naked or enclosed in a fruit.

4. The plant kingdom is also classified into two groups:
Cryptogams – Non-flowering and non-seed bearing plants.
Phanerogams – Flowering and seed-bearing plants.
– The plant kingdom has been classified into five subgroups according to the above-
mentioned criteria:
– Thallophyta
– Bryophyta
– Pteridophyta
– Gymnosperms
– Angiosperms
Cryptogams
Phanerogams

6. Thallophyta
– Thallophytes lack a well-differentiated body structure and the
plant body is thallus like.
– Thallophytes: Primitive plants where the body is not differentiated
into stem, roots and leaves
they may be filamentous, colonial, branched or unbranched.
Common examples are Volvox, Fucus, Spirogyra, Chara, Polysiphonia,
Ulothrix, etc.

7. Characteristics of Thallophyta
– They are usually found in moist or wet places.
– This is due to the absence of “true roots” and vascular tissue that is needed to transport water
and minerals. Hence they are found in moist or wet places.
– They are autotrophic in nature.
– Most members of this group manufacture their own food. But a few members like fungi are
dependent on other sources of food.,
– Reserve food is generally starch.
– After photosynthesis, glucose is produced and consumed almost immediately, the remaining
glucose is converted into complex compounds called starch.
– They have a cell wall composed of cellulose around their cells.
– Absence of vascular tissue.
– Unlike other plants, xylem and phloem are absent. etc
– Sex organs are simple, single-celled, there is no embryo formation after fertilization.

8. – Bryophytes do not have vascular tissues.
– The plant body has root-like, stem-like and leaf-like structures.
Bryophytes are terrestrial plants but known as “amphibians of the plant
kingdom” as they require water for sexual reproduction. They are
present in moist and shady places.
– Bryophyta includes mosses, hornworts and liverworts. Some of the
common examples are Marchantia, Funaria, Sphagnum, Antheoceros,
etc

9. Characteristics of Bryophytes
– Plants in this category do not have roots but have crude stems and leaves.
– They have “rhizoids” instead of roots which helps the plant to anchor to surface.
– These roots or rhizoids do not absorb nutrients like other usual plant roots.
– Mosses release spores from their leaves which travels by water and make new
mosses in new locations.
– Water is very essential for mosses to grow and spread. They can entirely dry out
and survive. When in contact with water, they again revive and continue
growing

10. Pteridophyta
– Pteridophytes have a well-differentiated plant body into root, stem and leaves.
They have a vascular system for conduction of water and other substances.
Some of the common examples are Selaginella, Equisetum, Pteris, etc.

11. characteristics of Pteridophytes
– Primary characteristics of Pteridophytes are as follows:
– They are seedless, vascular plants that show true alternation of generations.
Furthermore, the sporophyte has true roots, stem and leaves.
– They reproduce by spores, which are developed in sporangia.
– They may be homosporous or heterosporous.

12. Gymnosperms
– Gymnosperms have a well-differentiated plant body and vascular tissues. They
bear naked seeds, i.e. seeds are not enclosed within a fruit. Some of the
common examples of gymnosperms are Cycas, Pinus, Ephedra, etc.

13. Angiosperms
– Angiosperms are seed-bearing vascular plants with well-differentiated plant
body.
– The seeds of angiosperms are enclosed within the fruits.
– Angiosperms are widely distributed and vary greatly in size, e.g. Wolffia is small
measuring about 0.1 cm and Eucalyptus trees are around 100 m tall.
– Angiosperms are further divided into monocotyledons and dicotyledons
according to the number of cotyledons present in the seeds.
– Some of the common examples are mango, rose, tomato, onion, wheat, maize,
etc.

14. – Angiosperms are vascular plants with stems, roots, and leaves.
– The seeds of the angiosperm are found in a flower. These make up the majority
of all plants on earth.
– The seeds develop inside the plant organs and form fruit. Hence, they are also
known as flowering plants.
– Angiosperms are the most advanced and beneficial group of plants. They can
grow in various habitats as trees, herbs, shrubs, and bushes.

15. Classification of Angiosperm
– Monocotyledons
– The seeds have a single cotyledon.
– The leaves are simples and the veins are
parallel.
– This group contains adventitious roots.
– Each floral whorl has three members.
– It has closed vascular bundles and large
in number.
– For eg., banana, sugarcane, lilies, etc.
– Dicotyledons
– The seeds of these plants have two
cotyledons.
– They contain tap roots, instead of
adventitious roots.
– The leaves depict a reticulate venation.
– The flowers are tetramerous or
pentamerous and the vascular bundles
are organized in rings.
– For eg., grapes, sunflower, tomatoes, etc

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